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18 pages, 6225 KiB

Open AccessArticle

An Energy Modulation Interrogation Technique for Monitoring the Adhesive Joint Integrity Using the Full Spectral Response of Fiber Bragg Grating Sensors

by Chow-Shing Shin, Tzu-Chieh Lin and Shun-Hsuan Huang

Sensors 2025, 25(1), 36; https://doi.org/10.3390/s25010036 - 25 Dec 2024

Viewed by 460

Abstract

Adhesive joining has the severe limitation that damages/defects developed in the bondline are difficult to assess. Conventional non-destructive examination (NDE) techniques are adequate to reveal disbonding defects in fabrication and delamination near the end of service life but are not helpful in detecting [...] Read more.

Adhesive joining has the severe limitation that damages/defects developed in the bondline are difficult to assess. Conventional non-destructive examination (NDE) techniques are adequate to reveal disbonding defects in fabrication and delamination near the end of service life but are not helpful in detecting and monitoring in-service degradation of the joint. Several techniques suitable for long-term joint integrity monitoring are proposed. Fiber Bragg grating (FBG) sensors embedded in the joint are one of the promising candidates. It has the advantages of being close to the damage and immune to environmental attack and electromagnetic interference. Damage and disbonding inside an adhesive joint will give rise to a non-uniform strain field that may bring about peak splitting and chirping of the FBG spectrum. It is shown that the evolution of the full spectral responses can closely reveal the development of damages inside the adhesive joints during tensile and fatigue failures. However, recording and comparing the successive full spectra in the course of damage is tedious and can be subjective. An energy modulation interrogation technique is proposed using a pair of tunable optical filters. Changes in the full FBG spectral responses are modulated by the filters and converted into a conveniently measurable voltage output by photodiodes. Monitoring damage development can then be easily automated, and the technique is well-suited for practical applications. Filter spectrum width of 5 nm and initial overlap with the FBG spectrum to give 40% of the maximum output voltage is found to be optimal for measurement. The technique is tested on embedded FBGs from different adhesive lap-joint specimens and successfully reflected the severity of changes in the full spectral shapes during the course of tensile failure. Moreover, the trends in these PD outputs corroborate with the V value previously proposed to describe the qualitative change in FBG spectral shape. Full article

(This article belongs to the Special Issue Feature Papers in Physical Sensors 2024)

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18 pages, 4311 KiB

Open AccessArticle

Light-Emitting Diode Array with Optical Linear Detector Enables High-Throughput Differential Single-Cell Dielectrophoretic Analysis

by Emerich Kovacs, Behnam Arzang, Elham Salimi, Michael Butler, Greg E. Bridges and Douglas J. Thomson

Sensors 2024, 24(24), 8071; https://doi.org/10.3390/s24248071 - 18 Dec 2024

Viewed by 389

Abstract

This paper presents a lens-free imaging approach utilizing an array of light sources, capable of measuring the dielectric properties of many particles simultaneously. This method employs coplanar electrodes to induce velocity changes in flowing particles through dielectrophoretic forces, allowing the inference of individual [...] Read more.

This paper presents a lens-free imaging approach utilizing an array of light sources, capable of measuring the dielectric properties of many particles simultaneously. This method employs coplanar electrodes to induce velocity changes in flowing particles through dielectrophoretic forces, allowing the inference of individual particle properties from differential velocity changes. Both positive and negative forces are detectable. The light source utilized in this system is composed of LEDs with a wavelength of 470 nm, while detection is performed using a 256-element optical array detector. Measurements with 10 μm polystyrene beads demonstrate this method can resolve changes equivalent to a Clausius–Mossotti factor of 0.18. Simulations in this work, using values from the literature, predict that Clausius–Mossotti factor differences of 0.18 are sufficient to differentiate viable from nonviable cells and cancerous from multidrug-resistant cancerous cells. We demonstrate that for Chinese hamster ovary (CHO) cells, the method can collect a dielectric response spectrum for a large number of cells in several minutes. We demonstrate that for CHO cells, Clausius–Mossotti factor differences of 0.18 can be discriminated. Due to its simple detection apparatus and the utilization of high-throughput, wide, clog-resistant channels, this method holds promise for a wide range of applications. Full article

(This article belongs to the Special Issue Feature Papers in Physical Sensors 2024)

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23 pages, 8746 KiB

Open AccessArticle

Development of Inductive Current Transformer 400/5/1 of Class 0.2S for Frequency Range 50 Hz–5 kHz

by Michal Kaczmarek and Blazej Pacholczyk

Sensors 2024, 24(24), 8011; https://doi.org/10.3390/s24248011 - 15 Dec 2024

Viewed by 639

Abstract

This paper is devoted to the development of a window-type inductive current transformer (iCT) with a rated primary current equal to 400 A and two secondary windings with rated currents of 5 A and 1 A. Its novelty concerns the presentation of this [...] Read more.

This paper is devoted to the development of a window-type inductive current transformer (iCT) with a rated primary current equal to 400 A and two secondary windings with rated currents of 5 A and 1 A. Its novelty concerns the presentation of this process in the case of an iCT with a 0.2S accuracy class ensured not only for a sinusoidal current of a frequency of 50 Hz but also for the transformation of distorted current in the harmonic frequency range from 50 Hz to 5 kHz. The maximum permissible values of the current error and phase displacement are equal to ±0.2% and ±0.2°, respectively, and are the same as the limiting values for a 50 Hz sinusoidal current of a rated RMS value. In the design process, three materials were considered for the construction of the developed iCT 400/5/1: electrical steel, permalloy and nanocrystalline (Nano). Their wideband properties were analyzed and the choice of the Nano magnetic core was justified with the already-available data in the literature on the basis of elaborated design assumptions. In order to specify its particular type, four magnetic cores with different initial magnetic permeabilities were tested. It was demonstrated that, as far as more favorable magnetic properties also involved increased active power losses in the magnetic core, it was not an appropriate choice for the construction of the iCT, especially for the transformation of the current with a main frequency equal to 50 Hz or 60 Hz. Full article

(This article belongs to the Special Issue Feature Papers in Physical Sensors 2024)

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18 pages, 1732 KiB

Open AccessArticle

A One-Dimensional Depthwise Separable Convolutional Neural Network for Bearing Fault Diagnosis Implemented on FPGA

by Yu-Pei Liang, Hao Chen and Ching-Che Chung

Sensors 2024, 24(23), 7831; https://doi.org/10.3390/s24237831 - 7 Dec 2024

Viewed by 592

Abstract

This paper presents a hardware implementation of a one-dimensional convolutional neural network using depthwise separable convolution (DSC) on the VC707 FPGA development board. The design processes the one-dimensional rolling bearing current signal dataset provided by Paderborn University (PU), employing minimal preprocessing to maximize [...] Read more.

This paper presents a hardware implementation of a one-dimensional convolutional neural network using depthwise separable convolution (DSC) on the VC707 FPGA development board. The design processes the one-dimensional rolling bearing current signal dataset provided by Paderborn University (PU), employing minimal preprocessing to maximize the comprehensiveness of feature extraction. To address the high parameter demands commonly associated with convolutional neural networks (CNNs), the model incorporates DSC, significantly reducing computational complexity and parameter load. Additionally, the DoReFa-Net quantization method is applied to compress network parameters and activation function outputs, thereby minimizing memory usage. The quantized DSC model requires approximately 22 KB of storage and performs 1,203,128 floating-point operations in total. The implementation achieves a power consumption of 527 mW at a clock frequency of 50 MHz, while delivering a fault diagnosis accuracy of 96.12%. Full article

(This article belongs to the Special Issue Feature Papers in Physical Sensors 2024)

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16 pages, 2868 KiB

Open AccessArticle

First Stability Characterization for a CZT Detection System in an e⁺e⁻ Collider Environment

by Leonardo Abbene, Francesco Artibani, Manuele Bettelli, Antonino Buttacavoli, Fabio Principato, Andrea Zappettini, Massimiliano Bazzi, Giacomo Borghi, Mario Bragadireanu, Michael Cargnelli, Marco Carminati, Alberto Clozza, Francesco Clozza, Luca De Paolis, Raffaele Del Grande, Kamil Dulski, Laura Fabbietti, Carlo Fiorini, Carlo Guaraldo, Mihail Iliescu, Masahiko Iwasaki, Aleksander Khreptak, Simone Manti, Johann Marton, Pawel Moskal, Fabrizio Napolitano, Szymon Niedźwiecki, Hiroaki Ohnishi, Kristian Piscicchia, Yuta Sada, Francesco Sgaramella, Diana Laura Sirghi, Florin Sirghi, Magdalena Skurzok, Michal Silarski, Antonio Spallone, Kairo Toho, Lorenzo Toscano, Marlene Tüchler, Oton Vasquez Doce, Johann Zmeskal, Catalina Curceanu and Alessandro Scordo Show full author list Hide full author list

Sensors 2024, 24(23), 7562; https://doi.org/10.3390/s24237562 - 27 Nov 2024

Viewed by 541

Abstract

The SIDDHARTA-2 collaboration has developed a novel X-ray detection system based on cadmium-zinc-telluride (CZT, CdZnTe), marking the first application of this technology at the DA

Φ

NE electron-positron collider at INFN-LNF. This work aims to demonstrate the stability of the detectors’ performance in [...] Read more.

The SIDDHARTA-2 collaboration has developed a novel X-ray detection system based on cadmium-zinc-telluride (CZT, CdZnTe), marking the first application of this technology at the DA

Φ

NE electron-positron collider at INFN-LNF. This work aims to demonstrate the stability of the detectors’ performance in terms of linearity and resolution over short and long periods, thereby establishing their suitability for precise spectroscopic measurements within a collider environment. A reference calibration spectrum is presented in association with findings from assessments of linearity and resolution stability. Additionally, this study introduces a validated model of the response function of the detector. The relative deviations from the nominal values for the source transitions, obtained by fitting the entire spectrum with a background function and the previously introduced response function, are reported. Finally, a comparison of the calibration performance with and without beams circulating in the collider’s rings is presented. These promising results pave the way for applying CZT detectors in kaonic atom studies and, more generally, in particle and nuclear physics spectroscopy. Full article

(This article belongs to the Special Issue Feature Papers in Physical Sensors 2024)

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40 pages, 9583 KiB

Open AccessArticle

Development of Advanced Positioning Techniques of UWB/Wi-Fi RTT Ranging for Personal Mobility Applications

by Harris Perakis, Vassilis Gikas and Günther Retscher

Sensors 2024, 24(23), 7520; https://doi.org/10.3390/s24237520 - 25 Nov 2024

Viewed by 505

Abstract

“Smart” devices, such as contemporary smartphones and PDAs (Personal Digital Assistance), play a significant role in our daily live, be it for navigation or location-based services (LBSs). In this paper, the use of Ultra-Wide Band (UWB) and Wireless Fidelity (Wi-Fi) based on RTT [...] Read more.

“Smart” devices, such as contemporary smartphones and PDAs (Personal Digital Assistance), play a significant role in our daily live, be it for navigation or location-based services (LBSs). In this paper, the use of Ultra-Wide Band (UWB) and Wireless Fidelity (Wi-Fi) based on RTT (Round-Trip Time) measurements is investigated for pedestrian user localization. For this purpose, several scenarios are designed either using real observation or simulated data. In addition, the localization of user groups within a neighborhood based on collaborative navigation (CP) is investigated and analyzed. An analysis of the performance of these techniques for ranging the positioning estimation using different fusion algorithms is assessed. The methodology applied for CP leverages the hybrid nature of the range measurements obtained by UWB and Wi-Fi RTT systems. The proposed approach stands out due to its originality in two main aspects: (1) it focuses on developing and evaluating suitable models for correcting range errors in RF-based TWR (Two-Way Ranging) technologies, and (2) it emphasizes the development of a robust CP engine for groups of pedestrians. The results obtained demonstrate that a performance improvement with respect to position trueness for UWB and Wi-Fi RTT cases of the order of 74% and 54%, respectively, is achieved due to the integration of these techniques. The proposed localization algorithm based on a P2I/P2P (Peer-to-Infrastructure/Peer-to-Peer) configuration provides a potential improvement in position trueness up to 10% for continuous anchor availability, i.e., UWB known nodes or Wi-Fi access points (APs). Its full potential is evident for short-duration events of complete anchor loss (P2P-only), where an improvement of up to 53% in position trueness is achieved. Overall, the performance metrics estimated based on the extensive evaluation campaigns demonstrate the effectiveness of the proposed methodologies. Full article

(This article belongs to the Special Issue Feature Papers in Physical Sensors 2024)

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15 pages, 18055 KiB

Open AccessArticle

Precise Mechanical Oscillator Design and Calibration for Characterising Sub-Millimetre Movements in mmWave Radar Systems

by Felipe Parralejo, Fernando J. Álvarez, José A. Paredes, Fernando J. Aranda and Teodoro Aguilera

Sensors 2024, 24(23), 7469; https://doi.org/10.3390/s24237469 - 22 Nov 2024

Viewed by 567

Abstract

For many industrial and medical applications, measuring sub-millimetre movements has become crucial, for instance, for the precise guidance of surgical robots. The literature shows the feasibility of millimetre-wave (mmWave) radars to deal with such micro-vibrations. However, the availability of reference devices to configure [...] Read more.

For many industrial and medical applications, measuring sub-millimetre movements has become crucial, for instance, for the precise guidance of surgical robots. The literature shows the feasibility of millimetre-wave (mmWave) radars to deal with such micro-vibrations. However, the availability of reference devices to configure and test these systems is very limited. This work proposes the design of a mechanical oscillator to characterise sub-millimetre vibration detection and measurement using a mmWave radar. The final implementation is fully controllable in both amplitude and frequency. Additionally, it can be wirelessly controlled and synchronised with other systems. Its functioning was experimentally calibrated and tested using the sub-millimetre motion capture system OptiTrack. It was tested to generate low-frequency oscillations from 0.80 Hz to 3.50 Hz with reliable peak amplitudes of 0.05 mm and above, with less than 6% peak amplitude relative error. Finally, the device was used to characterise a 60 GHz mmWave radar with those values. Full article

(This article belongs to the Special Issue Feature Papers in Physical Sensors 2024)

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23 pages, 2249 KiB

Open AccessArticle

Improved EMAT Sensor Design for Enhanced Ultrasonic Signal Detection in Steel Wire Ropes

by Immanuel Rossteutscher, Oliver Blaschke, Florian Dötzer, Thorsten Uphues and Klaus Stefan Drese

Sensors 2024, 24(22), 7114; https://doi.org/10.3390/s24227114 - 5 Nov 2024

Viewed by 909

Abstract

This study is focused on optimizing electromagnetic acoustic transducer (EMAT) sensors for enhanced ultrasonic guided wave signal generation in steel cables using CAD and modern manufacturing to enable contactless ultrasonic signal transmission and reception. A lab test rig with advanced measurement and data [...] Read more.

This study is focused on optimizing electromagnetic acoustic transducer (EMAT) sensors for enhanced ultrasonic guided wave signal generation in steel cables using CAD and modern manufacturing to enable contactless ultrasonic signal transmission and reception. A lab test rig with advanced measurement and data processing was set up to test the sensors’ ability to detect cable damage, like wire breaks and abrasion, while also examining the effect of potential disruptors such as rope soiling. Machine learning algorithms were applied to improve the damage detection accuracy, leading to significant advancements in magnetostrictive measurement methods and providing a new standard for future development in this area. The use of the Vision Transformer Masked Autoencoder Architecture (ViTMAE) and generative pre-training has shown that reliable damage detection is possible despite the considerable signal fluctuations caused by rope movement. Full article

(This article belongs to the Special Issue Feature Papers in Physical Sensors 2024)

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26 pages, 12355 KiB

Open AccessArticle

Embroidered Transmission Lines with Conductive Yarns: Challenges, Modeling, Fabrication, and Experimental Performance Assessment

by Chrysanthi Angelaki, Aris Tsolis, Sofia Bakogianni and Antonis A. Alexandridis

Sensors 2024, 24(21), 6961; https://doi.org/10.3390/s24216961 - 30 Oct 2024

Viewed by 736

Abstract

This paper presents an enhanced measurement technique for evaluating embroidered transmission lines (TLs), based on a TL characterization method. The evaluation metric is the “pure” losses of the embroidered TL excluding mismatch losses. Enhanced mechanical stability and removability of embroidered samples under a [...] Read more.

This paper presents an enhanced measurement technique for evaluating embroidered transmission lines (TLs), based on a TL characterization method. The evaluation metric is the “pure” losses of the embroidered TL excluding mismatch losses. Enhanced mechanical stability and removability of embroidered samples under a test is supported by a specially designed measurement setup. Losses are used to find the effective conductivity of each embroidery pattern. Various embroidered samples are fabricated, measured, and evaluated. The repeatability of measurements and fabrication are analyzed and assessed, resulting in average deviations of 0.5 dB and 0.7 dB, respectively. A comparative evaluation of two different yarns of low and high conductivity is presented. Single and double stitching patterns for each yarn are manufactured with stitch densities of 1–7 lines/mm. For interconnection with SMA connectors, a conductive fabric contact (CFC) was selected as the finish of the TL, as a more practical interface instead of direct yarn contact (YC). The analysis of the measurements proved useful findings, such as an increase in the stitch density or the amount of yarn used does not always improve the performance; the use of double stitching greatly improves low-performance stitch densities; the effective conductivity of embroidery patterns changes with frequency; the YC interface yields more losses for medium stitch densities, but for higher stich densities, it presents an improved performance compared with the CFC interconnection. Full article

(This article belongs to the Special Issue Feature Papers in Physical Sensors 2024)

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15 pages, 2137 KiB

Open AccessArticle

Research on Abnormal State Detection of CZ Silicon Single Crystal Based on Multimodal Fusion

by Lei Jiang, Haotan Wei and Ding Liu

Sensors 2024, 24(21), 6819; https://doi.org/10.3390/s24216819 - 23 Oct 2024

Viewed by 724

Abstract

The Czochralski method is the primary technique for single-crystal silicon production. However, anomalous states such as crystal loss, twisting, swinging, and squareness frequently occur during crystal growth, adversely affecting product quality and production efficiency. To address this challenge, we propose an enhanced multimodal [...] Read more.

The Czochralski method is the primary technique for single-crystal silicon production. However, anomalous states such as crystal loss, twisting, swinging, and squareness frequently occur during crystal growth, adversely affecting product quality and production efficiency. To address this challenge, we propose an enhanced multimodal fusion classification model for detecting and categorizing these four anomalous states. Our model initially transforms one-dimensional signals (diameter, temperature, and pulling speed) into time–frequency domain images via continuous wavelet transform. These images are then processed using a Dense-ECA-SwinTransformer network for feature extraction. Concurrently, meniscus images and inter-frame difference images are obtained from the growth system’s meniscus video feed. These visual inputs are fused at the channel level and subsequently processed through a ConvNeXt network for feature extraction. Finally, the time–frequency domain features are combined with the meniscus image features and fed into fully connected layers for multi-class classification. The experimental results show that the method can effectively detect various abnormal states, help the staff to make a more accurate judgment, and formulate a personalized treatment plan for the abnormal state, which can improve the production efficiency, save production resources, and protect the extraction equipment. Full article

(This article belongs to the Special Issue Feature Papers in Physical Sensors 2024)

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17 pages, 3575 KiB

Open AccessArticle

An Electronic “Tongue” Based on Multimode Multidirectional Acoustic Plate Wave Propagation

by Nikita Ageykin, Vladimir Anisimkin, Andrey Smirnov, Alexander Fionov, Peng Li, Zhenghua Qian, Tingfeng Ma, Kamlendra Awasthi and Iren Kuznetsova

Sensors 2024, 24(19), 6301; https://doi.org/10.3390/s24196301 - 29 Sep 2024

Cited by 1 | Viewed by 810

Abstract

This paper theoretically and experimentally demonstrates the possibility of detecting the five basic tastes (salt, sweet, sour, umami, and bitter) using a variety of higher-order acoustic waves propagating in piezoelectric plates. Aqueous solutions of sodium chloride (NaCl), glucose (C₆ [...] Read more.

This paper theoretically and experimentally demonstrates the possibility of detecting the five basic tastes (salt, sweet, sour, umami, and bitter) using a variety of higher-order acoustic waves propagating in piezoelectric plates. Aqueous solutions of sodium chloride (NaCl), glucose (C₆H₁₂O₆), citric acid (C₆H₈O₇), monosodium glutamate (C₅H₈NO₄Na), and sagebrush were used as chemicals for the simulation of each taste. These liquids differed from each other in terms of their physical properties such as density, viscosity, electrical conductivity, and permittivity. As a total acoustic response to the simultaneous action of all liquid parameters on all acoustic modes in a given frequency range, a change in the propagation losses (ΔS₁₂) of the specified wave compared with distilled water was used. Based on experimental measurements, the corresponding orientation histograms of the ΔS₁₂ were plotted for different types of acoustic waves. It was found that these histograms for different substances are individual and differ in shape, area, and position of their extremes. Theoretically, it has been shown that the influence of different liquids on different acoustic modes is due to both the electrical and mechanical properties of the liquids themselves and the mechanical polarization of the corresponding modes. Despite the fact that the mechanical properties of the used liquids are close to each other, the attenuation of different modes in their presence is not only due to the difference in their electrical parameters. The proposed approach to creating a multi-parametric multimode acoustic electronic tongue and obtaining a set of histograms for typical liquids will allow for the development of devices for the operational analysis of food, medicines, gasoline, aircraft fuel, and other liquid substances without the need for detailed chemical analysis. Full article

(This article belongs to the Special Issue Feature Papers in Physical Sensors 2024)

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14 pages, 3209 KiB

Open AccessArticle

Spiral Annealing of Magnetic Microwires

by Alexander Chizhik, Paula Corte-Leon, Valentina Zhukova, Juan Mari Blanco, Julian Gonzalez and Arcady Zhukov

Sensors 2024, 24(19), 6239; https://doi.org/10.3390/s24196239 - 26 Sep 2024

Viewed by 531

Abstract

A preprocessing technique named “spiral annealing” was applied for the first time to magnetic microwires. In this process, the sample was arranged in a flat spiral shape during annealing, and subsequent measurements were conducted on the unbent sample with the induced stress distribution [...] Read more.

A preprocessing technique named “spiral annealing” was applied for the first time to magnetic microwires. In this process, the sample was arranged in a flat spiral shape during annealing, and subsequent measurements were conducted on the unbent sample with the induced stress distribution along and transverse to the sample. The research utilized both magnetic and magneto-optical methods. The anisotropy field magnitude in both the volume and surface of the microwire was measured, and for the first time, a direct correlation between the anisotropy field and the curvature of a spirally annealed microwire was established. Additionally, a connection between the type of surface domain structure and the degree of spiral curvature was identified. The preservation of the distribution of spiral annealing-induced magnetic properties both along and across the microwire is a key effect influencing the technological application of the microwire. The range of induced curvature within which a specific helical magnetic structure can exist was also determined. This insight links the conditions of spiral annealing to the selection of microwires as active elements in magnetic sensors. Full article

(This article belongs to the Special Issue Feature Papers in Physical Sensors 2024)

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11 pages, 2684 KiB

Open AccessArticle

Investigation of Graphene Single Layer on P-Type and N-Type Silicon Heterojunction Photodetectors

by Carmela Bonavolontà, Antonio Vettoliere, Marianna Pannico, Teresa Crisci, Berardo Ruggiero, Paolo Silvestrini and Massimo Valentino

Sensors 2024, 24(18), 6068; https://doi.org/10.3390/s24186068 - 19 Sep 2024

Viewed by 649

Abstract

Photodetectors are of great interest in several technological applications thanks to their capability to convert an optical signal into an electrical one through light–matter interactions. In particular, broadband photodetectors based on graphene/silicon heterojunctions could be useful in multiple applications due to their compelling [...] Read more.

Photodetectors are of great interest in several technological applications thanks to their capability to convert an optical signal into an electrical one through light–matter interactions. In particular, broadband photodetectors based on graphene/silicon heterojunctions could be useful in multiple applications due to their compelling performances. Here, we present a 2D photodiode heterojunction based on a graphene single layer deposited on p-type and n-type Silicon substrates. We report on the electro-optical properties of the device that have been measured in dark and light conditions in a spectral range from 400 nm to 800 nm. The comparison of the device’s performance in terms of responsivity and rectification ratio is presented. Raman spectroscopy provides information on the graphene single layer’s quality and oxidation. The results showcase the importance of the doping of the silicon substrate to realize an efficient heterojunction that improves the photoresponse, reducing the dark current. Full article

(This article belongs to the Special Issue Feature Papers in Physical Sensors 2024)

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22 pages, 14713 KiB

Open AccessArticle

A Proposed Non-Destructive Method Based on Sphere Launching and Piezoelectric Diaphragm

by Cristiano Soares Junior, Paulo Roberto Aguiar, Doriana M. D’Addona, Pedro Oliveira Conceição Junior and Reinaldo Götz Oliveira Junior

Sensors 2024, 24(18), 5874; https://doi.org/10.3390/s24185874 - 10 Sep 2024

Viewed by 648

Abstract

This work presents the study of a reproducible acoustic emission method based on the launching of a metallic sphere and low-cost piezoelectric diaphragm. For this purpose, tests were first conducted on a carbon fiber-reinforced polymer structure, and then on an aluminum structure for [...] Read more.

This work presents the study of a reproducible acoustic emission method based on the launching of a metallic sphere and low-cost piezoelectric diaphragm. For this purpose, tests were first conducted on a carbon fiber-reinforced polymer structure, and then on an aluminum structure for comparative analysis. The pencil-lead break (PLB) tests were also conducted for comparisons with the proposed method. Different launching heights and elastic deformations of the structures were investigated. The results show higher repeatability for the sphere impact method, as the PLB is more affected by human inaccuracy, and it was also effective in damage detection. Full article

(This article belongs to the Special Issue Feature Papers in Physical Sensors 2024)

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13 pages, 1614 KiB

Open AccessArticle

One-Port Coaxial Line Sample Holder Characterisation Method of Dielectric Spectra

by Iman Farhat, Lourdes Farrugia, Julian Bonello, Rafel Grima, Raffaele Persico and Charles Sammut

Sensors 2024, 24(17), 5573; https://doi.org/10.3390/s24175573 - 28 Aug 2024

Viewed by 716

Abstract

A technique for solving the one-port closed coaxial transmission line sample holder scattering equation for complex permittivity inversion for lossy materials is presented. A non-linear least-squares procedure is used for the determination of parameters for the specification of the spectral functional form of [...] Read more.

A technique for solving the one-port closed coaxial transmission line sample holder scattering equation for complex permittivity inversion for lossy materials is presented. A non-linear least-squares procedure is used for the determination of parameters for the specification of the spectral functional form of the complex permittivity. The method allows for accurate retrieval of many low- and high-permittivity dielectric materials in the frequency range of 1 GHz to 3 GHz inserted into the coaxial cell. Using this method, the complex permittivity of a number of liquids and a Maltese soil known as Bajjad soil have been extracted by measurements using a short terminated coaxial transmission line sample holder. The proposed novel inversion method is mainly based on the reflection coefficient of the test material. The measured results of the complex permittivity of liquid dielectrics such as ethanol, methanol, and TX100 are validated and compared with previously published data obtained from measurements made by the National Physical Laboratory (NPL) using a two-port measurement setup made with the same commercial coaxial transmission line sample holder used in the one-port setup. Since the technique allows broadband measurements, it has been used to characterise the soil dielectric spectrum in the frequency range of 1–3 GHz, which is also compared with results from a two-port setup of the same coaxial line. The experimental results are a validation of the proposed approach for different types of materials. Full article

(This article belongs to the Special Issue Feature Papers in Physical Sensors 2024)

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22 pages, 2481 KiB

Open AccessArticle

An Application of Uncertainty Quantification to Efficiency Measurements and Validating Requirements through Correlating Simulation and Physical Testing Results

by Michael Leighton and Uday Akasapu

Sensors 2024, 24(15), 4867; https://doi.org/10.3390/s24154867 - 26 Jul 2024

Viewed by 821

Abstract

Validation is a critical aspect of product development for meeting design goals and mitigating risk in the face of considerable cost and time commitments. In this research article, uncertainty quantification (UQ) for efficiency testing of an Electric Drive Unit (EDU) is demonstrated, considering [...] Read more.

Validation is a critical aspect of product development for meeting design goals and mitigating risk in the face of considerable cost and time commitments. In this research article, uncertainty quantification (UQ) for efficiency testing of an Electric Drive Unit (EDU) is demonstrated, considering confidence in simulations with respect to the validation campaign. The methodology used for UQ is consistent with the framework mentioned in the guide to the expression of uncertainty in measurement (GUM). An analytical evaluation of the measurement chain involved in EDU efficiency testing was performed and elemental uncertainties were derived, later to be propagated to the derived quantity of efficiency. When uncertainties were associated with measurements, the erroneous measurements made through sensors in the measurement chain were highlighted. These results were used for the assessment of requirement coverage and the validation of test results. Full article

(This article belongs to the Special Issue Feature Papers in Physical Sensors 2024)

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18 pages, 5434 KiB

Open AccessArticle

A Method of Precise Auto-Calibration in a Micro-Electro-Mechanical System Accelerometer

by Sergiusz Łuczak, Magdalena Ekwińska and Daniel Tomaszewski

Sensors 2024, 24(12), 4018; https://doi.org/10.3390/s24124018 - 20 Jun 2024

Viewed by 970

Abstract

A novel design of a MEMS (Micro-Electromechanical System) capacitive accelerometer fabricated by surface micromachining, with a structure enabling precise auto-calibration during operation, is presented. Precise auto-calibration was introduced to ensure more accurate acceleration measurements compared to standard designs. The standard mechanical structure of [...] Read more.

A novel design of a MEMS (Micro-Electromechanical System) capacitive accelerometer fabricated by surface micromachining, with a structure enabling precise auto-calibration during operation, is presented. Precise auto-calibration was introduced to ensure more accurate acceleration measurements compared to standard designs. The standard mechanical structure of the accelerometer (seismic mass integrated with elastic suspension and movable plates coupled with fixed plates forming a system of differential sensing capacitors) was equipped with three movable detection electrodes coupled with three fixed electrodes, thus creating three atypical tunneling displacement transducers detecting three specific positions of seismic mass with high precision, enabling the auto-calibration of the accelerometer while it was being operated. Auto-calibration is carried out by recording the accelerometer indication while the seismic mass occupies a specific position, which corresponds to a known value of acting acceleration determined in a pre-calibration process. The diagram and the design of the mechanical structure of the accelerometer, the block diagram of the electronic circuits, and the mathematical relationships used for auto-calibration are presented. The results of the simulation studies related to mechanical and electric phenomena are discussed. Full article

(This article belongs to the Special Issue Feature Papers in Physical Sensors 2024)

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12 pages, 2757 KiB

Open AccessArticle

Multi-Parameter Characterization of Liquid-to-Ice Phase Transition Using Bulk Acoustic Waves

by Andrey Smirnov, Vladimir Anisimkin, Natalia Voronova, Vadim Kashin and Iren Kuznetsova

Sensors 2024, 24(12), 4010; https://doi.org/10.3390/s24124010 - 20 Jun 2024

Cited by 2 | Viewed by 847

Abstract

The detection of the liquid-to-ice transition is an important challenge for many applications. In this paper, a method for multi-parameter characterization of the liquid-to-ice phase transition is proposed and tested. The method is based on the fundamental properties of bulk acoustic waves (BAWs). [...] Read more.

The detection of the liquid-to-ice transition is an important challenge for many applications. In this paper, a method for multi-parameter characterization of the liquid-to-ice phase transition is proposed and tested. The method is based on the fundamental properties of bulk acoustic waves (BAWs). BAWs with shear vertical (SV) or shear horizontal (SH) polarization cannot propagate in liquids, only in solids such as ice. BAWs with longitudinal (L) polarization, however, can propagate in both liquids and solids, but with different velocities and attenuations. Velocities and attenuations for L-BAWs and SV-BAWs are measured in ice using parameters such as time delay and wave amplitude at a frequency range of 1–37 MHz. Based on these measurements, relevant parameters for Rayleigh surface acoustic waves and Poisson’s modulus for ice are determined. The homogeneity of the ice sample is also detected along its length. A dual sensor has been developed and tested to analyze two-phase transitions in two liquids simultaneously. Distilled water and a 0.9% solution of NaCl in water were used as examples. Full article

(This article belongs to the Special Issue Feature Papers in Physical Sensors 2024)

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21 pages, 21117 KiB

Open AccessArticle

Novel Reference Method for the Characterization of PD Measuring Systems Using HFCT Sensors

by Eduardo Arcones, Fernando Álvarez, Javier Ortego and Fernando Garnacho

Sensors 2024, 24(12), 3788; https://doi.org/10.3390/s24123788 - 11 Jun 2024

Cited by 1 | Viewed by 941

Abstract

During their lifespan, high-voltage (HV) electrical systems are subjected to operating conditions in which electrical, mechanical, thermal and environmental-related stresses occur. These conditions over time lead to unforeseen failures caused by various types of defects. For this reason, there are several technologies for [...] Read more.

During their lifespan, high-voltage (HV) electrical systems are subjected to operating conditions in which electrical, mechanical, thermal and environmental-related stresses occur. These conditions over time lead to unforeseen failures caused by various types of defects. For this reason, there are several technologies for measuring and monitoring the electrical systems, with the aim of minimizing the number of faults. The early detection of defects, preferably in their incipient state, will enable the necessary corrective actions to be taken in order to avoid unforeseen failures. These failures generally lead to human risks and material damage, lack of power supply and significant economic losses. An efficient maintenance technique for the early detection of defects consists of the supervision of the dielectrics status in the installations by means of on-line partial discharge (PD) measurement. Nowadays, there are numerous systems in the market for the measurement of PD in HV installations. The most efficient with a reasonable cost will be those that offer greater security guarantees and the best positioned in the market. Currently, technology developers and users of PD measuring systems face difficulties related to the lack of reference procedures for their complete characterization and to the technical and economic drawback of performing the characterization tests on site or in laboratory installations. To deal with the previous difficulties, in this paper a novel method for the complete and standardized characterization of PD measuring systems is presented. The applicability of this method is mainly adapted for the characterization of systems operating in on-line applications using high-frequency current transformer (HFCT) sensors. For the appropriate application of the method, an associated and necessary scale modular test platform is used. In the test platform, the real on-site measuring conditions of an HV insulated distribution line are simulated in a controlled way. Practical characterizations, showing the convenience and advantages of applying the method using the modular test platform, are also presented. Full article

(This article belongs to the Special Issue Feature Papers in Physical Sensors 2024)

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13 pages, 8165 KiB

Open AccessArticle

A Dual-Band Polarization-Insensitive Frequency Selective Surface for Electromagnetic Shielding Applications

by Muhammad Idrees, Yejun He, Shahid Ullah and Sai-Wai Wong

Sensors 2024, 24(11), 3333; https://doi.org/10.3390/s24113333 - 23 May 2024

Cited by 4 | Viewed by 1277

Abstract

This paper presents a novel polarization-insensitive dual-band frequency-selective surface (FSS)-based electromagnetic shield. The miniaturized FSS unit cell consists of a modified Jerusalem crossed loop and a corner-modified square loop. These FSS elements are arranged in a co-planner configuration over a single-layer Rogers 5880 [...] Read more.

This paper presents a novel polarization-insensitive dual-band frequency-selective surface (FSS)-based electromagnetic shield. The miniaturized FSS unit cell consists of a modified Jerusalem crossed loop and a corner-modified square loop. These FSS elements are arranged in a co-planner configuration over a single-layer Rogers 5880 substrate and simultaneously offer effective shielding in the X- and Ku-bands. Moreover, the FSS manifests polarization-independent and angularly stable band-reject filter characteristics over various oblique angles of incidence for both the TE and TM polarizations with virtuous attenuation at both resonances. In addition, the FSS structure is modelled into an equivalent lumped circuit to better analyze the phenomenon of EM wave suppression. A finite prototype of FSS is fabricated and tested. The simulated and measured results are in good agreement, thus making it a potential candidate for RF shielding/isolation applications. Full article

(This article belongs to the Special Issue Feature Papers in Physical Sensors 2024)

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14 pages, 4569 KiB

Open AccessArticle

Magnetoelectric Sensor Operating in d₁₅ Thickness-Shear Mode for High-Frequency Current Detection

by Fuchao Li, Jingen Wu, Sujie Liu, Jieqiang Gao, Bomin Lin, Jintao Mo, Jiacheng Qiao, Yiwei Xu, Yongjun Du, Xin He, Yifei Zhou, Lan Zeng, Zhongqiang Hu and Ming Liu

Sensors 2024, 24(8), 2396; https://doi.org/10.3390/s24082396 - 9 Apr 2024

Cited by 1 | Viewed by 1348

Abstract

For the application of high-frequency current detection in power systems, such as very fast transient current, lightning current, partial discharge pulse current, etc., current sensors with a quick response are indispensable. Here, we propose a high-frequency magnetoelectric current sensor, which consists of a [...] Read more.

For the application of high-frequency current detection in power systems, such as very fast transient current, lightning current, partial discharge pulse current, etc., current sensors with a quick response are indispensable. Here, we propose a high-frequency magnetoelectric current sensor, which consists of a PZT piezoelectric ceramic and Metglas amorphous alloy. The proposed sensor is designed to work under d₁₅ thickness-shear mode, with the resonant frequency around 1.029 MHz. Furthermore, the proposed sensor is fabricated as a high-frequency magnetoelectric current sensor. A comparative experiment is carried out between the tunnel magnetoresistance sensor and the magnetoelectric sensor, in the aspect of high-frequency current detection up to 3 MHz. Our experimental results demonstrate that the d₁₅ thickness-shear mode magnetoelectric sensor has great potential for high-frequency current detection in smart grids. Full article

(This article belongs to the Special Issue Feature Papers in Physical Sensors 2024)

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18 pages, 1457 KiB

Open AccessArticle

Development of a Robust Sensor Calibration for a Commercially Available Rising Platemeter to Estimate Herbage Mass on Temperate Seminatural Pastures

by Jessica Werner, Khaterine Salazar-Cubillas, Sari Perdana-Decker, Kilian Obermeyer, Elizabeth Velasco, Leonie Hart and Uta Dickhoefer

Sensors 2024, 24(7), 2326; https://doi.org/10.3390/s24072326 - 5 Apr 2024

Viewed by 1275

Abstract

Rising platemeters are commonly used in Ireland and New Zealand for managing intensive pastures. To assess the applicability of a commercial rising platemeter operating with a microsonic sensor to estimate herbage mass with its own equation, the objectives were (i) to validate the [...] Read more.

Rising platemeters are commonly used in Ireland and New Zealand for managing intensive pastures. To assess the applicability of a commercial rising platemeter operating with a microsonic sensor to estimate herbage mass with its own equation, the objectives were (i) to validate the original equation; (ii) to identify possible factors hampering its accuracy and precision; and (iii) to develop a new equation for heterogeneous swards. A comprehensive dataset (n = 1511) was compiled on the pastures of dairy farms. Compressed sward heights were measured by the rising platemeter. Herbage mass was harvested to determine reference herbage availability. The adequacy of estimating herbage mass was assessed using root mean squared error (RMSE) and mean bias. As the adequacy of the original equation was low, a new equation was developed using multiple regression models. The mean bias and the RMSE for the new equation were overall low with 201 kg dry matter/ha and 34.6%, but it tended to overestimate herbage availability at herbage mass < 500 kg dry matter/ha and underestimate it at >2500 kg dry matter/ha. Still, the newly developed equation for the microsonic sensor-based rising platemeter allows for accurate and precise estimation of available herbage mass on pastures. Full article

(This article belongs to the Special Issue Feature Papers in Physical Sensors 2024)

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